1. Field of the Invention
The present invention relates to transgenic soybean plants comprising event MON87769, progeny plants, and seed thereof. The event exhibits an oil composition comprising stearidonic acid. The invention also relates to methods for detecting the presence of said soybean event in a biological sample, and provides nucleotide sequences that are unique to the event.
2. Description of Related Art
Soybean is an important crop and is a primary food source in many areas of the world. The methods of biotechnology have been applied to soybean for improvement of agronomic traits and the quality of the product. One such quality trait is a soybean oil comprising stearidonic acid (SDA).
It would be advantageous to be able to detect the presence of transgene/genomic DNA of a particular plant in order to determine whether progeny of a sexual cross contain the transgene/genomic DNA of interest. In addition, a method for detecting a particular plant would be helpful when complying with regulations requiring the pre-market approval and labeling of foods derived from the recombinant crop plants.
The polyunsaturated fatty acids (PUFAs) are known to provide health benefits when consumed. An oil containing SDA, a PUFA, would be advantageous as part of a healthy diet in humans and other animals. SDA may be sourced from plant and animal sources. Commercial sources of SDA include the plant genera Trichodesma, Borago (borage) and Echium as well as fish. However, there are several disadvantages associated with commercial production of PUFAs from natural sources. Natural sources of PUFAs, such as animals and plants, tend to have highly heterogeneous oil compositions. The oils obtained from these sources therefore can require extensive purification to separate out one or more desired PUFAs or to produce an oil which is enriched in one or more PUFAs. Natural sources of PUFAs also are subject to uncontrollable fluctuations in availability. Fish stocks may undergo natural variation or may be depleted by over fishing. Fish oils also have unpleasant tastes and odors, which may be impossible to economically separate from the desired product and can render such products unacceptable as food supplements. Animal oils, and particularly fish oils, can accumulate environmental pollutants. Foods may be enriched with fish oils, but again, such enrichment is problematic because of cost and declining fish stocks worldwide. Nonetheless, if the health messages to increase fish intake were embraced by communities, there would likely be a problem in meeting demand for fish. Furthermore, there are problems with sustainability of this industry, which relies heavily on wild fish stocks for aquaculture feed (Naylor et al., Nature 405:1017-1024, 2000).
Therefore, it would be advantageous to produce a PUFA such as SDA in a land-based terrestrial crop plant system, which can be manipulated to provide production of commercial quantities of SDA. In commercial oilseed crops, such as canola, soybean, corn, sunflower, safflower, or flax, the conversion of some fraction of the mono and polyunsaturated fatty acids that typify their seed oil to SDA requires the seed-specific expression of the enzymes delta 6-desaturase and delta 15-desaturase. Oils derived from plants expressing elevated levels of Δ6- and Δ15-desaturases are rich in SDA. As there is also a need to increase omega-3 fatty acid intake in humans and animals, there is a need to provide a wide range of omega-3 enriched foods and food supplements so that subjects can choose feed, feed ingredients, food and food ingredients which suit their usual dietary habits. It is also advantageous to provide commercial quantities of SDA in a soy plant.
The expression of foreign genes in plants is known to be influenced by their chromosomal position, perhaps due to chromatin structure (e.g., heterochromatin) or the proximity of transcriptional regulation elements (e.g., enhancers) close to the integration site Weising et al. (Ann. Rev. Genet 22:421-477, 1988). For this reason, it is often necessary to screen a large number of events in order to identify an event characterized by optimal expression of an introduced gene of interest. For example, it has been observed in plants and in other organisms that there may be wide variation in the levels of expression of an introduced gene among events. There may also be differences in spatial or temporal patterns of expression, for example, differences in the relative expression of a transgene in various plant tissues, that may not correspond to the patterns expected from transcriptional regulatory elements present in the introduced gene construct. For this reason, it is common to produce several hundreds to several thousands different events and screen the events for a single event that has the desired transgene expression levels and patterns for commercial purposes. An event that has the desired levels or patterns of transgene expression is useful for introgressing the transgene into other genetic backgrounds by sexual outcrossing using conventional breeding methods. Progeny of such crosses maintain the transgene expression characteristics of the original transformant. This strategy is used to ensure reliable gene expression in a number of varieties that are suitably adapted to specific local growing conditions.
It is possible to detect the presence of a transgene by any well known nucleic acid detection method such as the polymerase chain reaction (PCR) or DNA hybridization using nucleic acid probes. These detection methods generally focus on frequently used genetic elements, such as promoters, terminators, marker genes, etc. As a result, such methods may not be event-specific (e.g. useful for discriminating between different events), particularly those produced using the same DNA construct, unless the sequence of chromosomal DNA adjacent to the inserted DNA (“flanking DNA”) is known. An event-specific PCR assay is discussed, for example, by Taverniers et al. (J. Agric. Food Chem., 53: 3041-3052, 2005) in which an event-specific tracing system for transgenic maize lines Bt11, Bt176, and GA21 and for canola event GT73 is demonstrated. In this study, event-specific primers and probes were designed based upon the sequences of the genome transgene junctions for each event. Event-specific detection methods may also be required by regulatory agencies charged with approving the use of transgenic plants comprising a given transformation event. Transgenic plant event specific DNA detection methods have also been described in U.S. Pat. Nos. 6,893,826; 6,825,400; 6,740,488; 6,733,974; 6,689,880; 6,900,014 and 6,818,807.